We found evidence that both heme produced in the liver and heme injected intravenously gains access to the systemic circulation and bile. Therefore, it can be assumed that a small hepatic "heme pool" exists to which and from which heme is transported. We plan to isolate liver cytosol proteins instrumental in this intra-hepatic transport of heme. These experiments in rats were performed in parallel with those in humans pertaining to the effect of intravenous heme injections on bile bilirubin and porphyrin flow.